This invention relates generally to integrated circuit packaging, and more specifically, to an improved integrated circuit package and method of attaching leads of the package to the I/O pads of an integrated circuit die. The attachments are made using conventional assembly processes, without using wire bonding.
As the speed and complexity of integrated circuits continue to increase, new and improved packaging techniques become necessary. Traditional packaging techniques are not always well suited for some applications. However, because of the high cost of purchasing capital equipment and new manufacturing technologies, it is desirable for a manufacturer to make such improvements without making major changes to the manufacturing process.
One aspect of packaging is the attachment of I/O pads of an integrated circuit die to the leads of the integrated circuit package. A traditional technique for making such an attachment is wire bonding. Wire bonding is a technique by which discrete wires are attached between the I/O pads and the leads. Though the technique is extensively used in the industry, wire bonding has several disadvantages. Among these disadvantages are the cost, the package size, and the heat sink properties of wirebonded packages. Another disadvantage is that the wire placed between an I/O pad and a package pin changes the characteristics of the device. For example, the wire adds inductance to the electrical path.
In some applications, this added inductance is not desirable. For example, the increased inductance will not allow the device to operate at the high switching speed of many of today's integrated circuits. The frequency at which the integrated circuits operate is continually increasing. In the past, the inductance of the wire was not an important factor. However, as speeds increase, it becomes more significant.
Because of these higher operating frequencies, the use of gallium arsenide integrated circuits is increasing in the industry. Gallium arsenide integrated circuits are now often found in many wireless communications, TVs, VCRs, and other similar electronics. Traditional silicon integrated circuits cannot match the high frequencies of gallium arsenide. Silicon reaches its operating peak at around 2.5 MHz. However, gallium arsenide integrated circuits can operate at frequencies approaching 30 GHZ. At such high speeds, traditional wirebonding, with its relatively high inductance, is not a practical packaging technique.
Another packaging technique that has been introduced is TAB (tape automated bonding.) However, TAB has not been well received in the industry. Several factors have contributed to its lack of success. For example, TAB requires its own specialized assembly equipment. This makes it expensive to switch to a TAB processing system. Furthermore, reliability problems are often associated with TAB packaging. For example, humidity may cause tape used in the TAB process to delaminate. Also, TAB technology does not provide any protection to the integrated circuit die during the manufacturing process because the integrated circuit die remains exposed throughout the process.
In light of these and other disadvantages associated with conventional techniques, there is a need for a new technology for packaging integrated circuits. An improved packaging technique is therefore desirable.